Apparatus for determining the weight and center of gravity of vehicles



June 8, 1948.

Filed Feb. 28, 1944 W. W. H. DEAN APPARATUS FOR DETERMINING THE WEIGHTAND CENTER OF GRAVITY OF VEHICLES 2 Sheets-Sheet l ,PERB TiN/(5 w r uEg'l'l/cf- Mani/vr iM/Ycir 3 I l yJullie 8, 1948. w w H DEAN 2,443,098

MINING THE WEIGHT AND APPARATUS PoR iaETR Y CENTER OF GRAVITY 0FVEHICLES Filed Feb. 28, 1944 2 Sheets-Sheet 2 U caA/PA/rmyrfzaae f//W 5V7 AIMA l sistors comprising Patented June 8, 1948 APPARATUS ORDETERMINING THE WEIGHT AND CENTER F GRAVITY 0F VEHICLES William W. H.Dean, Poin ada, assigner to Radio a corporation of Deia te Claire,Quebec, Can- Corporation of America, A ware Application February 28,1944, Serial No. 524,277 12 Cla'llnl. (Cl. i3-65) This invention relatesgenerally to measuring apparatus and more particularly to an improvedmeans for determining the total loaded weight and the location of thecenter of gravity of loaded vehicles.

More particularly, the invention contemplates the use of a pair ofbalanced Wheatstone bridges which provide separate electrical means fordeitermining the total loaded weight and the total oaded responsive tothe weight and the moment determining means for indicating the center ofgravity of the loaded vehicle.

The invention may comprise one oi two principal forms, each of whichinclude two separately adjustable Wheatstone bridges. The bridges may beactuated by manually adjusting a and then by manually adjusting the.balancing resistive arm of each ci the bridges until each bridge isbalanced. A modification oi' the system comprises means for installingvariable resistive portions of the loaded vehicle, and separate meansfor adjusting said resistors in accordance with the actual loaddistribution throughout the vehicle. The bridge balancing resisitve armsthence may be manually adjusted to balance the bridges, or they may beactuated by the bridge balancing indicator circuit automatically tobalance the bridge.

Brieiiy, each bridge comprises two iixed reflxed ratio arms, preferablyhaving a resistance ratio of 1 to 1, an adjustable bridge balancingresistor arm, and a fourth series resistive arm comprising a pluralityof separately adjustable serially connected variable resistors eachcharacteristic oi' the loaded Weight or the loaded moment of apredetermined portion oi the loaded vehicle. The various seriesresistors of the fourth bridge arm are actuated separately eithermanually or by means of the loading weight as described hereinafter.After the bridge is balanced, the total loaded Weight is indicated as afunction of the adjustment of the weight bridge balanced arm, and thecenter oi gravity, with respect to an arbitrarily iixed reference point,is indicated by a second indicator diii'erentially connected to theweight and moment bridge balance adjustable resistors.

Among the objects of the invention are to provide an improved means formeasuring the loading weight of a vehicle. Another object of theinvention is to provide an improved means for the resistors 2determining the moments of the various portions or a loaded vehicle. Afurther object of the invention is to provide an improved means fordetermining the total loading weight and the center of gravity oialoaded vehicle.

Further objects of the invention include means providing an electricalmethod for calculating the load distribution characteristics oi' aloaded vehicle. Another object of the invention is to provide Wheatstonebridge means, responsive to the load distribution and load moments cf aloaded vehicle, and means for balancing automatically said bridge meansto indicate the total weight and the center of gravity ci' said loadedvehicle. An -additional object of the invention is to provide animproved means for adjusting the resistance oi' a Wheatstone bridgecircuit element in response to the loading oi.' a predetermined portionof a loaded vehicle.

'I'he invention will be described in greater detail by reference to theaccompanying drawings of which Figure 1 is a schematic circuit diagramoi' one embodiment thereof, Figure 2 is a schematic'circuit diagram of asecond embodiment thereof, Figure 3 is a partially schematic tragmentaryelevational view of a. weight actuated bridge variable resistiveelement, and Figure 4 is a schematic circuit diagram of an automaticbridge balancing circuit for use with a D.,C. re sistive bridge. Similarreference characters are applied to similar elements throughout thedrawings.

Referring to Figure 1 of the drawings, a first resistive bridge Iincludes serially-connected rst and second equal resistive ratio arms l,5, respectively. 'I'he common terminals of the series resistors 3, I areconnected to one terminal 1 of a source cf alternating or directenergizing potential. The remaining terminal of the second resistor 5 isconnected to one terminal of an adjustable bridge balancing resistor 9,and to one terminal of a first null detector II. The remaining terminalof the rst bridge resistor 3 is connected to the remaining terminal ofthe first null detector I I and to one terminal I 2 of a weightdetermining resistive network I3. The remaining terminal I 4 of theweight determining resistivenetwork I3 is connected to the remainingterminal i6 of the bridge balancing resistor 9 to form a closed seriesresistive circuit including 3, 5, S and the network Il. The commonterminal of the resistive network I3 and the balancing resistor 9 isconnected to one xed contact of a single-pole, double-throw switch' I5.

ated by the actual unknown loading weights. In

I the latter arrangement, the resistive elements are lirst and secondbridge ratio arms 3, 5, and to the terminal 1 of the source ofenergizing potential. The remaining terminals or the third and fourthratio arms 23, l are connected to a second null detector 3i. The commonterminals of the fourth ratio arm 25 and the second null devdisposed,for example, under weight responsive portions of the vehicle compartmentfloors, whereby the load applied to the oor varies the resistance rofcorresponding `resistive elements which are-Irlv connected toy theremainder of the y bridge 'network through suitable cables, not

- shown.

tector 3l are connected to one terminal or a mo- 'ment balancing bridgearm 29. The remaining terminal of the third bridge ratio arm 23 isconnected to one terminal 32 of a moment determining resistive network33. The remaining ter` minal 34 of the moment determining resistivenetwork 33 is connected to the remaining terminal of the momentbalancing resistor 29 and to the remaining fixed contact of the switchI5.

The first null detector II, connected in the first bridge I, isconnected to a iii-st motor 35 which is arranged to actuate the weightbalancing resistor 9 to balance the bridge i for all adjustments of theweight determining resistive network I3. The operation of the nulldetector and motor for actuating the weight balancing resi-Stor will bedescribed in detail hereinafter. The adjustment of the weight balancingresistor 9 actuates a weight indicator 31 which may be calibrated interms of vehicle total load weight.

Similarly, the second null detector 3i, connected to the ,second bridge2l, is connected to the second motor 39 which actuates the momentbalancing `resistor 29 to balance automatically the second bridge 2I forall adjustments 6I the resistors of the moment determining network 33. Amechanical differential 40, interconnecting the actuating mean-s of theweight balancing resistor 9 and the moment balancing resistor 29,actuates a second indicator 4I which may be calibrated in terms of thecenter of gravity of the loaded vehicle, since the differential couplingprovides means for indicating the total moment, as determined by thesecond bridge 2|, divided by the total weight, as determined by thebridge I thereby indicating the center of gravity of the vehicle.

The weight determining resistive network I3 includes a plurality ofserially connected separately adjustable resistors 43, 45, 41, 49, 5I,53, 55, 51, 59, 6I, 63 and 55, each of which may be adjusted separatelyto represent the total load weight of the various portions of thevehicle indicated on the drawing. The moment determining network 33,connected in the second bridge 2 I, includes asimilar serially-connectedgroup of individually adjustable resistors 43', 45', 41', 49', 5I', 53',55', 51', 59', 9i", 63', 65' and 61 each of which adjustable resistiveelements are ganged with the corresponding resistive element 0i theweight determining network I3. Adjustment of the weight determiningresistor for a predetermined portion of the loaded vehicle therebyadjusts a corresponding resistor in the moment determining network 33which varies the resistance in the moment determining network as afunction of the moment of the particular loading Weight.

'I'he various adjustable resistors of the weight determining network I3and the moment determining network 33 may be actuated manually as afunction of individual known weights loaded in each portion of thevehicle, or they may be actu- The mechanical differential mechanism 49which interconnects the adjusting means on the weight balancing resistor9 and the moment balancing resistor 29, may be any type of diiierentialgearing mechanism known in the art which will provide diirerentialindications for the center of gravity indicator 4I in response toadjustments of the weight and moment balancing resistors.

If desired, the first and second motors 35, 39

may beomitted, and the lirst and second nuli detector circuitssimplified to comprise merely bridge balancing meters, whereby thebridge balancing resistors are adjusted to provide null indications onsaid meters in the usual manner of balancing Wheatstone bridges.

Referring to Figure 2, the weight and moment determining bridges I, 2icomprise similar ratio arms 3, '5 and 23, 25, similar weight balancingand moment balancing adjustable resistive arms 9, 29, and similar weightdetermining networks I3 land 33 to the elements described in the circuitof Figure 1. Similarlyya weight indicatorV 31 actuated by theadjustmentcf the weight balancing resistor 9, and a center of gravityindicator 4I, actuated by the differential mechanism 49 in response todifferential adjustments of the weight balancing and moment balancingresistors 9, 29, may be actuated by either motor control or by manualadjustment, as described for the circuit of Fig. 1. y

A single null detector Il and a single motor 35, connected,respectively, through switches` 1I, 13,' 15, may be selectivelyconnected to either bridge network I, 2I and the motor 35 may beselectively connected to actuate either balancing resistor 9, 29.

The moment determining network.93 comprises a plurality of fixedmultiplying resistors 43", 45", 1u su 5IN, 53H, 55u 51u' sus", sin e31165", 61" and $9 which are selectively connected in parallel with theadjustable resistors 43, 45, 41, 49, 5l', 53, 55, 51, 59, 6I, 53, 55 ofthe weight determining network I3 by means of ganged switches 11, 19,8l, 83, 95, 91, 99, 9|, 93, 95, 91 and 99. The dash line IUI,interconnecting all of the switches 1I, 13, 15, 11, 19, 8l, 93, 85, 81.99, 9i, 93, 95, 91 and 99 indicates thatvall of said switches may beganged for unitary control whereby for one position of the switches theweight determining network I3 is operative, and for the alternateposition of the switches the iixed moment determining network 33isoperatively combined with the adjustable weight network i3.

Therefore, in the iirst position of the switches,

mature |45 of the motor 5 l resistor Il is subsequently actuated. Themotor may be omitted ancing resistors 3, 2l adjusted manually, ii.'desired. A Similarly, if the motor is omitted, the null indicator needcomprise only a conventional bridge balance indicating meter.

The characteristics of the various iixed resistive elements comprisingthe moment determining' by springs |09 and guided by pistons operatingin guide cylinders ||3. The adjustable resistive elements may be of thecompression type, as indicated schematically by the resistor H5,interposed between the movable floor |||1 and the base portion ||1 ofthe compartment, or by a slider-type resistance H9, wherein a movableresistor contact |2| is pivoted at |23 and actuated by the movablecompartment floor |51 through a lever arm |25. The variable resistorelements ||5 or Il! may be terminated outside of the vehicle compartmentin any convenient manner for connection to suitable cables connectingthe resistors to the bridge network. It should be understood that theparticular mechanical construction of the compartment floor and resistoractuating elements is included for the purpose of illustration, and thatvarious other mechanical modifications thereof may be employed such asthe use of pressure or liquid level for uid loads.

The null indicators ii, 3|, and the motors 35, 33 responsive thereto forautomatically actuating the weight and moment bridge balancing resistors3, 23, may be of any type known in the art such as, for example, thetype of self-orienting mech- Aanism employed in self-orienting radiodirection finders orvfollow-up devices. If the resistance bridges I, 2|are energized by a source of direct current, the null indicator circuitmay comprise a relatively simple thermionic tube network of the typedisclosed in Figure 4, and the motors 35, 38 may be D.C. motors having aconventional armature and two oppositely phased ileld windings.

In the circuit of Figure 4, the null detectors of the circuits of Figs.1 or 2 are connected to the end terminals |33, |31,'of a center-tappedhigh resistor |3i, the center tap of which may be grounded. One inputterminal |33, connected to one arm of the bridge, is connected to thecontrol electrode of a first thermionic tube |35. 'I'he remaining inputterminal |31, connected to the opposite bridge arm, is connected to thecontrol electrode of a second thermionic tube |35. The cathodes of thefirst and second thermionic tubes |35, |33-are connected together, andconnected to ground through a conventional cathode bias resistor I 4Iand bypass capacitor |43. The anodes of the first and second thermionictubes |35, |38 are connected to opposite ends of the motor fieldwindings |45, |41, respectively. v The remaining terminals of the neldwindings |45, |41 are connected together, and connected to a source ofanode potential (not shown) for energizing the neld windings and theanode circuits. The 1aris connected in the customary manner throughbrushes to the source of D.C. energizing potential.

auaoos entirely and the bridge bale When the resistive bridges areenergized from a source ot alternating potential, the null detectorcircuit and motor actuating circuit may be somewhat more complicated.With this arrangement, a practical solution is round by employing atwophase A.C. motor onewinding of which is energized in phase with thepotential source connected to the bridge, and the remaining winding oi'which is energized at a phase which approaches quadrature therewith asthe bridge approaches balance. Many modiilcations of this arrangementare known instant application. Further description herein of thespeciilc circuits which might be employed for self-balancing of an A.-C.bridge of the type described as such circuits are well known to thoseskilled in the art.

Thus the invention disclosed comprises two embodiments, and severalmodifications thereof, of an improved means for electrically determiningthe total loaded weight and the center of gravity of loaded vehicles.The system described provides an extremely convenient and accuratemethod of determining load characteristics and load distribution whichprovides greater flexibility, speed, and accuracy than known mechanicalload measuring or computing systems. It should be understood that theparticular circuit constants of the resistor networks |3, 33 must bedetermined for each different type and variety of vehicle.

I claim as my invention:

l. Electrical apparatus for determining the weight and center of gravityof a vehicle including a. first bridge network, a second bridge network,means for adjusting said first network as a function of said vehicleweight, means for balancing said nrst network, means responsive to saidnetwork balance adjusting means for indicating said weight, means foradjusting said second network as a function of the mechanical moments ofpredetermined portions of said vehicle, means for balancing said secondnetwork, and diiferential means responsive to said balance adjustingmeans of both of said networks for indicating the center of gravity ofsaid vehicle.

2. Electrical apparatus for determining the weight and the center ofgravity of a loaded vehicle including a first bridge network, a -secondbridge network, means for electrically energizing said networks, rstmeans for adjust-ing said iirst network in accordance with the loadingof said vehicle, second adjusting means for balancing said firstnetwork, means for indicating the total load of said vehicle inaccordance with said adjustment of said second adjusting means, thirdmeans for adjusting said second network in accordance with themechanical moments of predetermined portions of said vehicle. fourthadjusting means for balancing said second network, and differentialmeans for indicating the center of gravity of said loaded vehicleresponsive to said adjustments of said second and said fourth adjustingmeans.

3. Electrical apparatus for determining the weight and the center ofgravity of a loaded vehicle including a first Wheatstone bridge network,a second Wheatstone bridge network, means for electrically energizingsaid networks, :tirst means for adjusting at least one portion of saidfirst network in accordance with the loading ot said vehicle, secondadjusting means for iirst network, means for indiload of said vehicle inaccordance with said adjustment of said second adjusting means, thirdmeans for adjusting at least one portion of said second network inaccordance with the mechanical moments of predetermined portions of saidvehicle, fourth adjusting means for balancing said second network, anddifferential means for indicating the center of gravity of said loadedvehicle responsive to said adjustments of said second and said fourthadjusting means.

4. Electrical apparatus for determining the weight andthe center ofgravity of a loaded vehicle including a first Wheatstone bridge network,a second Wheatstone bridge network, means for electrically energizingsaid networks, first means for adjusting at least one portion of saidfirst network in accordance with the loading of said vehicle, secondadjusting means for balancing said iirst network, means mechanicallyconnected to said second adjusting means for indicating the total loadof said vehicle in accordance with said adjustment of said secondadjusting means, third means for adjusting at least one portion of saidsecond network in accordance with the mechanical moments ofpredetermined portions of said vehicle, fourth adjusting means forbalancing said second network, and diiferential means mechanicallyconnected to said second and fourth adjusting means for indicating thecenter of gravity .of said loaded vehicle as a function of saidadjustments of said second and said fourth adjusting means.

5. Electrical apparatus for determining the weight and the center ofgravity of a loaded vehicle including a first Wheatstone resistivebridge network, a s'econd Wheatstone resistive bridge network, means forelectrically energizing said networks, ilrst variable resistive meansfor adjusting at least one portion of said first network in accordancewith the loading of said vehicle, second variable resistive adjustingmeans for balancing said first network, means -mechanically connected tosaid second adjusting means for indicating the total Vload of saidvehicle in accordance with said adjustment of said second balancing saidcating the total 8 sponsive to one of said current detecting devices foradjusting said second and said fourth bridge adjusting means until saidbridge networks are balanced with respect to said current detectingdevices.

8. Electrical apparatus for determining the weight and the center ofgravity of a loaded vehicle including a nrst bridge network, a secondbridge network, means for selectively electrically energizing saidnetworks, first means for adjusting said ilrst network loading of saidvehicle, second adjusting means for balancing said first network, meansfor indicating the total load oi. said vehicle in accordance with saidadjustment of said second adjusting means, third means for adjustingsaid second network in accordance with the mechanical moments ofpredetermined portions of said vehicle, fourth adjusting means forbalancing said second network, and differential means for indicating thecenter of gravity of said loaded vehicle responsive to said adjustmentsof said second and said fourth adjusting means.

9. Apparatus of the typedescribed in claim 2 characterized in that saidbalancing means for said first and said second bridge networks includesa common current detecting device connected selectively to saidnetworks, an electromechanical device responsive to said currentdetecting device for adjusting selectively said second and said fourthbridge adjusting means until said bridge networks are balanced withrespect 'to said current detecting device, and common means forselectively energizing said bridge networks and for connecting saidnetworks to said current detecting device.

l0. Electrical apparatus for determining the weight and the center ofgravity of a loaded vehicle including a iirst bridge network, a secondbridge network, means for electrically energizing said networks, ilrstmeans including a pluraladjusting means, third variable resistive meansfor adjusting at least one portion of said second network in accordancewith the mechanical moments of predetermined portions of said vehicle,fourth variable resistive adjusting means for lbalancing said secondnetwork, and diierential means mechanically connected to said second andfourth'adjusting means for indicating the center of gravity of saidloaded vehicle as a function of said adjustments of said second and saidfourth adjusting means. Y

6. Apparatus of the type described in claim 2 characterized in that saidbalancing means for said rst and said second bridge networks includes aplurality of current detecting devices each connected to one oi' saidnetworks, and a plurality of electro-mechanical devices each responsiveto one of said current detecting devices for adjusting said second andsaid fourth bridge, adjusting means until said bridge networks arevbalanced with respect to said current detecting devices. v7. Apparatusof the type described in claim 5 characterized in that said balancingmeans for lsaid first and said secondl bridge networks includes aplurality of current: detecting devices each connected to one of saidnetworks, and a plurality of electromechanical devices each reity ofweight responsive impedance elements disposed at predetermined points insaid vehicle and connected to said first network for adjusting saidfirst network in accordance with the loading of said vehicle, secondadjusting means for balancing said iirstnetwork, means for indicatingthe total load of said vehicle in accordance with said adjustment ofsaid second adjusting means, third means including a plurality of otherweight responsive impedance elements disposed at other predeterminedpoints in said vehicle and connected `to said second network foradjusting said second network in accordance with the mechanical momentsof predetermined portions of said vehicle, fourth adjusting means forbalancing said second network, and differential means for indicating thecenter of gravity of said loaded vehicle responsive to said adjustmentsof said second and said fourth adjusting means.

1l. Electrical apparatus for determining the weight and the center ofgravity of a loaded vehicle including a. iirst bridge network,l a secondbridge network, means for electrically energizing said networks, i-lrstmeans including a plurality of weight responsive impedance elementsdisposed at predetermined points in said vehicle and connected to saidrst network for adjusting said first network in accordance with theloading of said vehicle, second adjusting means for balancing said rstnetwork, means for indicating the total load of said vehicle inaccordance with said adjust# ment of said second adjusting means, thirdmeans including means for selectively connecting said weight responsiveelements to said second netin accordance with the work for adjustingsaid second network in accordance with the mechanical moments ofpredetermined portions of said vehicle, fourth adjustand differentialmeans for indicating the ,center of gravity of said loaded vehicleresponsive to said adjustments of said second and said fourth adjustingmeans.

12. Electrical apparatus for determining the weight and center ofgravity of a vehicle including a first network, a second network, meansfor adjustmg said rst network asA a function of said vehicle weight,further means for adjusting said first network, means responsive to saidrst netdetermlned portions of said vehicle, further means for adjustingsaid second network, and differential means responsive to both of saidfurther adjusting means of both of said networks for indicating thecenter of gravity or said vehicle.

W. W. H. DEAN.

10 REFERENCES CITED The following references are oi' record in the tileof this paten UNITED STATES PATENTS Number Name Date 1,407,078 MurrayFeb. 21, 1922 1,515,995 Bryce Nov. 18, 1924 l1,826,762 Franklin Oct. 13,1931 2,123,142 McMaster July 5, 1938 2,179,822 Imm Nov. 14, 19392,255,814 Roche Sept. 16, 1941 2,336,142 Watson Dec. 7, 1943 2,373,503Schlieben et al. Apr. 10, 1945 FOREIGN PATENTS Number Country Date GreatBritain Feb. 16, 1933

